The US government Tuesday approved an anti-piracy mechanism that will make it harder for computer users to illegally distribute digital TV programs on the Internet. The goal is to speed the transition to higher quality digital broadcasts and ensure such programming remains free.

Broadcasters and the movie industry had urged the Federal Communications Commission to take such action, while consumer groups said it will force some people to purchase new electronics.

Some people already share TV shows and movies online, though the practice is limited by the speed of Internet connections — it can take many hours to transfer high-quality copies.

But as Internet connections get faster and broadcasters switch to much clearer digital television, the movie and television industries fear consumers will put high-quality copies of shows and films on the Web that others can download for free. This would reduce the broadcasters' ability to sell the shows for syndication or overseas.

The music industry saw CD sales fall as free music sharing proliferated on the Internet. It has started to sue listeners who illegally distribute songs online.

The five-member FCC voted unanimously to allow a "broadcast flag" to be added to digital programming to block broader distribution on the Internet, though the two Democrats on the panel expressed some reservations. Republican FCC Chairman Michael Powell called it "an important step toward preserving the viability of free over-the-air television."

In its order, the FCC told makers of digital television receivers that by July 1, 2005, their models must recognize the flag, an electronic signal that broadcasters can embed in their programs.

The commission said the order applies only to electronics equipment that can receive digital broadcast signals, not digital VCRs, DVD players and personal computers without digital tuners.

Congress already has told the TV industry to switch their broadcasts by 2007 to a digital format, which uses computer language, from the current analog format, which uses radio signals sent as waves. After the switch over, consumers who don't subscribe to a cable or satellite service would need digital tuners, either inside a TV or in a set-top box.

FCC officials said the flag would not prevent consumers from using existing or new DVD or VCR machines to make copies of TV programs. But the signal is designed to make it more difficult for consumers to then transfer those copies to the Internet and make them available to potentially millions of others free of charge.